i6o 



NATURE 



[June 15. 1893 



specimens illustrate :— (i) The rate of growth of the oyster. (2) 

 Natural varieties of the shells. (3) Modifications of a variety 

 bred under new conditions. 



Prof. T. McKenny Hughes, F.R.S., exhibited abnormal and 

 normal forms of oyster shells. The collection included oyster 

 shells, showing the great variety of abnormal forms produced by 

 accidental change in the position of the shells during growth, 

 and also a selection of oyster shells, showing that among recent 

 shells of O. edzilii most of the forms occur which are considered 

 of specific value in fossils. 



The Joint Eclipse Committee exhibited the following photo- 

 graphs taken during the recent Eclipse Expeditions to West Africa 

 and Brazil, (i) Photographs of the corona, taken in West Africa. 

 (2) Photographs of the spectra of the corona and prominences, 

 taken in West Africa. (3) Photographs of the corona, taken in 

 Brazil. (4) Photographs of the spectra of the corona, and 

 prominences, taken with the objective prism in Brazil. (5) 

 Photographs of the stations. 



Mr. W.H. Preece, F.R. S., exhibited submarine borersandspeci- 

 mens of submarine cables damaged by them. The Xylophaga and 

 Limnoria terebrans have proved serious and expensive depreda- 

 tors in tropical seas, but while twenty years ago limnoria was 

 practically unknown in our English waters, it has now 

 gradually spread all around our coasts, and cables have to be 

 served with brass tape to be protected from its attacks. Some 

 stones pierced by Saxicava rugosa were also shown. They came 

 from the Plymouth Breakwater. Several specimens of dam- 

 aged cables from different parts of the world were exhibited. 



The Zoological Society of London exhibited (i) a series of 

 living Canadian walking-stick xmecls {Diapheromera femorata), 

 hatched from eggs laid in the Society's insect-house in 1892. 

 The "Walking-sticks" are orthopterous insects of the family 

 Phasmidas, so-called from their resemblance to sticks. They 

 are strictly herbivorous, and clo-ely imitate the plants upon 

 which they feed, changing colour as the foliage turns in autumn. 

 In North America the present species is said to do great injury 

 to the oaks. These specimens are fed on hazel-leaves. (2) 

 Living specimens of the Hornet Clearwing Moth of the Oiier 

 (Sesia bembUifonnis], rearei from pupas in the Society's Insect- 

 house. This moth affords one of the best known examples of 

 "mimicry." Although belonging to quite a different order of 

 insects, it resembles a hornet so closely as to deceive a casual 

 observer, especially when it is on the wing. 



Col. Swinhoe exhibited some species of butterflies, illustrating 

 protective mimicry. Mimetic forms of the nymphalid genus 

 Hypolimnas in India, Malayana and Africa, showing the various 

 phases of development of mimicry in two widespread species 

 of the same genus; also mimetic resemblances to different 

 protected species in the females of Euripus halilherses, &c. 



Prof. H. G. Seeley, F. R. S. , exhibited fossil skulls from the Karoo 

 Rocks of Cape Colony. These specimens were brought from 

 Cape Colony by the exhibitor in 18S9. They include examples 

 of the chief types of fossil reptiles included in the Anomodont 

 and Theriodont groups, preferable to the genera Dicynodon 

 and Tapinocephalus. 



Mr. Edward Whymper exhibited the Corry "protected" 

 aneroid, a new form of aneroid, specially designed for use in 

 mountain-travel, or for aeronauts. This form of mountain 

 aneroid is designed to avoid the inaccuracies which result from 

 continued exposure to low atmospheric pressure. It is enclosed 

 in a perfectly air-tight outer case, and the internal atmosphere 

 is kept at about a normal pressure at all times, except when an 

 observation is to be taken, and then the cock is opened, and 

 communication with the external atmosphere is established. 

 After taking a reading, the pressure is restored to the normal 

 by means of a small force pump. The conditions thus corres- 

 pond to those which originally obtained, when the aneroid was 

 graduated under the air-pump receiver. 



Mr. J. W. Swan exhibited specimens of electrolytic copper, 

 deposited bright. A series of electrolytic copper deposits, 

 showing the great change produced in the character of the 

 deposited metal liy the addition of a minute quantity of colloid 

 matter to an acid solution of sulphate of copper. The deposits 

 produced from the solution containing the colloid are not only 

 bright instead of being dull, but they are also very much harder 

 and more elastic than ordinary electrolytic copper. 



Prof. Ilenrici, F. R.S., exhibited (i) A harmonic analyser, 

 constructed by G. Coradi, Ziirich, according to instructions by 

 Prof. Henrici and Mr. Sharpe. The instrument gives, on going 

 once over a curve, the first five terms of the expansion in 



NO. 1233, VOL 48] 



Fourier's series, and on going twice more over the curve, it gives 

 five additional terms. The constant term is not given. (2) 

 A calculating machine by Prof. Sellinger, constructed by Ott, 

 Munich. This instrument is constructed on altogether new 

 principles. The "carrying" is done continuously without 

 jerks. It works very rapidly and smoothly. 



In addition, Prof. J. Norman Lockyer, F.R.S.,gavea lecture 

 on the localities and instruments used during the eclipse of 

 April 16, 1893, in West Africa and Brazil, with photographs 

 showing some of the results obtained. 



Mr. W. M. Conway also used the electric lantern to show 

 photographic lantern slides, illustrating the scenery of the 

 Baltoro Gla;ier in the Karakoram Mountains, Kashmir, India. 

 The photographs were taken during Mr. Conway's climbing and 

 survey expedition in 1892. Some of them were taken from the 

 summit of the Pioneer Peak (22,500 ft.) ; the remainder repre- 

 sent the great mountains K2, Gtisherbrum, Masherbrum, the 

 Golden Throne, and others, probably the highest group of 

 mountains in the world. 



At intervals throughout the evening Mr. W^. Bayley Marshall 

 exhibited the lantern stereoscope (invented by Mr. John 

 Anderton). The images of a pair of stereoscopic transparencies 

 having been superposed on a lo-foot screen, the beams of light 

 from the two lanterns were polarised in planes at right angles to 

 each other. The picture was viewed through a pair of analysers, 

 similar to a small opera glass, and a true stereoscopic effec: was 

 obtained. 



THERMOMETER SOUNDINGS IN THE HIGH 

 A TMOSPHERE. 



'T'HE project, which was suggested by Le Verrier in 1874, of 

 sending small billoons into the upper atm )'iphere with 

 registering apparatus has been executed recently by M. Her- 

 mite, in Paris, with remarkable success. No fewer than thirteen 

 small balloons, constructed with paper and varnished with 

 petroleum, were liberated during the last four months of 1892, 

 and penetrated to an altitude of 9000 metres. A paper balloon 

 of 60 cubic metres capacity was sent up on December 7, but ex- 

 ploded at a snail distance from the earth. It was therefore 

 resolved to build a balloon of 113 cubic metres capacity in gold- 

 beaters' skin. The launching of this balloon took place 

 on March 21 last, at Vaugirard, with the help, of the 

 Aerophytic Union of France, of which I have the honour to 

 be the president. The balloon was filled with 1 13 cubic metres 

 of coal-gas. Its weight with netting was iibout fourteen 

 kilograms. It carried in a small basket a Richard register- 

 ing apparatus for temperature and pressure, and about seven 

 hundred postal-cards, to be liberated by the combustion of a 

 cotton string specially prepared for the purpose. This part of 

 the operation utterly failed. Although the fire was put to both 

 extremities of the string, it was extinguished before all the cards 

 had been sent down, and out of four hundred which were pre- 

 cipitated, no more than five or six were recovered. Thus, the 

 hope of determining the path by dropping such objects from an 

 immense height had proved futile. But the recovery of the 

 balloon at 190 km. from Paris was very easy, and the register- 

 ing apparatus was returned to its owner in excellent working 

 order. The diagram, which had been traced on the revolving 

 cylinder, has been submitted to a close inspection, of which the 

 results have been published in the Comptes Rendus and VAero- 

 phile, a new periodical devoted to the study of aeronautics. 



The registering of the pressure had been continued down to 

 95 mm. of mercury, which answers to something less than 

 17,000 metres, if Laplace's formula is valid even for this alti- 

 tude. A temperature had been registered of - 5i°C. =60° 

 below zero Fahr. at a level of about 14,000 metres, ac- 

 cording to the same formula. The temperature on the ground 

 being -f 17°, a diminution of 67° C. was thus found, which 

 is about a degree for each 210 metres. The atmosphere 

 being supposed to extend up to 180,000 metres, it is easy to 

 see that these numbers are an indication that the cold of the 

 upper regions is much greater than supposed according to 

 Fourier's theory, which asserts that the greatest degree of cold 

 observed at the surface of the earth, viz. 58° registered by 

 Black in Northern America is about equal to the temperature of 

 celestial space. 



This remarkable observation is not however to remain long 

 isolated, as Commander Renard, of Meudon, has built a set of 



